Evolution and Function of Antenna-Binding Proteins II in Recognition of Brassicaceous Volatiles by the Striped Flea Beetle

Antenna-binding proteins (ABPs) are crucial in behaviors, such as foraging in insects, but comprehensive studies on the evolution and functional characteristics of the whole family are rare. This study investigates the ABP II family in the striped flea beetle (<i>Phyllotreta striolata</i>), a major pest of Brassicaceae. Through phylogenetic, expression, and binding analyses, we characterized 38 odorant-binding proteins (OBPs) in the striped flea beetle and eight ABP II genes were distributed across four chromosomes. PstrOBP9 and PstrOBP24 exhibited high binding affinities to various volatiles of Brassicaceous plants, especially isothiocyanates (ITCs), and were coexpressed in the olfactory sensory neurons of the antennae. Individual RNAi knockdown of PstrOBP9 or PstrOBP24 had mild effects; however, dual knockdown abolished host-seeking and oviposition preferences, and there was an expression compensation phenomenon between them. These findings underscore the importance of ABP II in host volatile recognition and offer insights into developing behavior-based pest control strategies.